robinson



J. G. ROBINSON.

RECIPROCATING MECHANISM.

APPLICATION FILED JAN. 25. 1918.

1,325,657. Pgtented Dec; 23,1919.

a SHEETS-SHEET 1.

J. G. ROBINSON. v

RECIPROCATING MECHANISM.

APPLICATION FILED JAN. 25,1918- '1,325,657, Patented Dec; 23,1919.

4 3 SHEETS-SHEET 2- i 172729 WZZr/ (an? By UNITED STATES PAT onrion.

JAYG. ROBINSON, OF CHICAGO, ILLINOIS.

nnorrnocn'rmo nncnnmsm.

Patented Dec. 23, 1919.

Application filed January 25, 1918. Serial No. 213,650.

To all whom it may concern:

Be it known that I, JAY G. ROBINSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Reciprocating Mechanism, of which the following is a specification.

My invention is an improved mechanism for imparting a reciprocating movement without shock to mechanical elements and is particularly adapted, though not confined, to use in connection with fire box doors. In the following specification I describe the use of my invention as a means for actuating the fire box doors of a locomotive in which use the invention provides for the rapid opening and closing of the doors for firing, accomplishes this function without shock to an of the moving parts and by reason of the rapid opening and closing movements of the doors 'obviates the injuri- 011s eiiects resulting from the prolonged access of cold air to the interior of the fire box which is incident to manual operation.

In the drawings:

Figure 1 is a front elevation of a locomotive fire box door equipped with my invention.

Fig. 2 is a vertical sectional view of a valve, operated in this instance by a foot pedal, for controlling the movement of the doors,

Fig. 3' is a vertical central sectional view of a differential cylinder comprising chambers of difi'erent diameter and parts connected therewith, this difi'erential cylinder forming the main actuating means, and

Fig. 4 is a view similar to Fig. 3 showinga modified form of cylinder and operating connections.

As shown in Fig. 1, the door opening 1 of the fire box is provided with doors 2 and 8 slidably mounted upon vertical guides i and 5 and adapted each to close one half of the door opening, the doors in closed position meeting at the center of the door opening. The movement of the doors is caused by the reciprocation of the pistons 6 and 7 in the large and small chambers 8 and 9, respectively, of the differential cylinder 10. The pistons 6 and 7 are'connected by the piston rod 11, a downward continuation 12 of which projects beyond the end of the small partof the difierential cylinder where through a pin 13 it is pivotally connected to a link or connecting rod 14. For operating the upper door 2 a lever 15 is pivoted at 16, and for operating the lower door 3 a lever 17 is pivoted at 18. The pivots 16 and 18 form fixed centers or fulcrums upon which the levers 15 and 17 oscillate to cause the opening and closing of the doors. The lever 15 is connected to the upper door 2 through a short link 19 pivotally connected at its lower end to the lever by means of a pin 20 and at its upper end pivotally connected'to the door by means of a pin 21. The lower lever 17 is similarly connected to the lower door 3 by means of a short link 22 having a pivotal connection at its lower end to the lever through a-pin 23 and at its upper end a pivotal connection with the door through a pin 24. The lower end of the link or connecting rod 14 has a pivotal connection through a pin 25 with a lever 26 intermediate the ends thereof, the upper.

end of the lever- 26 being pivotally connected to the lever 15 by means of a pin 27 and the lower end being pivotally connected to the lever 17 by means of a pin 28. The ful crum 16 of the lever 15 being intermediate its point of connection with the upper door and with the lever 26 and the pivotal connection 28 of the lever 26 with the lever '17 being between the fulcrum 18 of the lever 17 and its point of connection with the door, it willbe' obvious that a. downward movement of the piston rod 12 acting through the link 14, lever 26 and levers l5 and 1-7 will impart a downward movement to the lower door and an upward movement to the upper door, thereby uncovering the door opening and that the reverse or closing movement will be effected by the upward movement of the piston rod 12. Briefly stated the movement of the doors is caused by alternately admitting'air or other fluid under pressure to and discharging the same from the upper end, as illustrated, of the large chamber 8 of the difi'erential cylinder 16, a constant supply of fluid pressure being maintained in the space between the pistons 6 and 7. The

end of the differential cylinder being open to the atmos here. The head 29 at the lower end 0 the differential cylinder is provided with an opening 30 of somewhat larger diameter than the extension 12 of the piston rod, thereby afi'ording free ingress and egress of air to and from the space below the smaller piston 7. Fluid under pressure is su plied to the upper end of the large chamber 8 through pipe 31 and to the space between the large and small pistons 6 and 7 through ipe 32 which communicates with the difigrential cylinder at a point just above the small chamber 9. The communicationof the pipe 32 with the difierential cylinder is controlled by' a check valve 33 which permits flow of fluid from the source of pressure through the pipe 32 into the differential cylinder, but prevents flowin the opposite direction. The check valve illu rated is of a usual form and provided with a disk 34 coiiperating with a valve seat formed ina diaphragm 35 extendin across the valve casing. The upper end ot the pipe 32 extends to any suitable source of fluid pressure such as the main air tankona. locomotive, and, in the arran ement of the parts shown in Fig. l, -the pipe 32 extends downwardly beyond the point of its connection with the difierential c linder and across to the left hand side 0 the door frame where connection is made at 36 with the casing of an operating valve 37. The pipe 31 designed to supply pressure fluid to the upper end of the difi erentlal cylinder likewise extends to a point of connection 38 with the casing of the operating valve 37. The connection of the valve controlled pipe 31 with the upper end of the differential cylinder is clearly shown in Fig. 3. The pipe 31 is threaded at 39 into the head 40 of the diflerential cylinder where communication is established with a duct 44 which communicates centrally with the extreme upper end of the differential cylinder. Located in-the duct 44'is a check valve 45 opening toward the interior of the cylinder. This check valve is of the usual type and co-acts with a horizontal seat formed at 46, the valve being designed to seat by gravity and to prevent outward flow of-pressure fiuid from the differential cylinder through the duct 44. The valve 45 is provided, however, with a small bleed opening 47 which permits a restricted outflow of pressure fluid from the upper end of the cylinder when the valve is seated. A second valve seat 48 is formed in the duct 44 and co-acts with a hand operated valve 49. The valve 49 is manipulated by means of a hand wheel 50 mounted upon the valve stem 51, the latter having the usual screwthreaded engagement with the valve casing.

By means of the valve 41) the rate of flow 0 pressure fluid, to and from the upper -is-provided at its through with a duct 42 which is formed in the cylin-' der wall and communicates with the interior of the cylinder at a point 43 some distance from the upper end thereof,

The actuatin valve is illustrated in detail in Fig. 2. he valve proper consists of a cylindrical stem or valve 52 adapted to be reciprocated vertically in the cylindrical bore of the valvecasin 37. A foot treadle 53 is fulcrumed at 54 wiereby de ression of the treadle elevates its rearwar and raises the valve 52, the latter stored to its lower position by air pressure when the treadle'is released. The valve 52 .upper end with a conical surface 55 adapted to seat upon the valve seat 56 formed in the casing 37 and is also provided with a central bore 57 communicating at its upper end with radial passages 58 and near its-lower end with radial passages 59, all of which radial passages extend from the bore 57 to the exterior of the valve stem 52. Extending around the valve stem 52, opposite the lower radial openings 59, is an. annular groove 60 into which the radial passages 59 open. The upper end ofthe extension being revalve casing 37 is closed, as illustrated, and

the fluid pressure casing 37 at a point above the valve seat 56. The pipe 31 communicateswith the interior of the valve casing 37 an opening 61 which. communicates with the annular groove 60. An exhaust opening 62 communicatingwith the atmosphere extends through the valve casing 37 below the opening 61..

at a point slightly The operation of the device is controlled b the foot valve. In- Fig. 2 the foot valve is shown in the position assumed when the foot treadle is released, thereby causing the doors to close. In the osition shown in Fig. 2 the valve stem 52- as been forced to its lower position and there held by the constant fiuid pressure supplied through the pipe 32. In this position thefiow of pressure fluid through the pipe 32 is arrested son of the conical head 55 of the valve stem being seated and the-upper end of the differential cylinder is in communication with the atmosphere through the pipe 31 which, in the lowered position of the valve stem 52, s in communication with the exhaust opening 62 through the annular groove 60. The pistons in the differential cylinder being in the position illustrated in Fig. '3 the fire box doors are open and when the foot trea by readle is released, as above described, the valve pipe 32 to its upper surface. When the valve 52 is forced to the position shown in Fig. 2 the upper part of the large chamber 8 of the diflerential cylinder is, as above stated, thrown into communication with'the atmosphere through pipe 31, valve casing 37 annular groove 60 and exhaust port 62. The

space between the pistons 6 and 7 in the dif opening 47 in the check valve 45 forms a by pass which permits a limited outflow of air through the duct it and pipe 31, and r after the large piston 6 uses to a point where it closes the duct 43 and is temporarily arrested the bleed opening 47 in the valve 45 affords the only means of escape of compressed air from the upper end of the differential cylinder and the restricted flow through the bleed opening eflects the requisite cushioning of the closing movement of the doors. When the operator desires to open the doors pressure upon the foot treadle elevates the stem 52- of the operating valve, thereby raising the annular groove 60 above the exhaust opening 62 and thereby cutting ofl communication between the pipe 31 and the atmosphere." At the same time the elevation of the valve stem 52 elevates the conical head 55 at the upper end of the valve stem and establishes communication between the fluid pressure pipe 32 and the pipe 31, this communication resultin the fact that the raising of the conica valve head 55 permits the pressure fluid to have access to the radial openings 58 in the valve stem 52 and through said radial openings, the bore 57 and radial openings 59 and annular groove 60 communication is established between the fluid pressure pipe 32 and the pipe 31. The communication so established results in a flow of compressed air or such other fluid as is used, into the duct 4.4: in the upper head of the differential cylinder, the fluid pressure elevating the check valve i5 and permitting free ingress of the fluid into the upper end of the cylinder. Thereupon the unbalanced pressure upon the upper surface of the upper piston 6 due to the constant admission of pressure fluid to the spacebetweenthepistons through the check valve 33 and the fluid under pressure, from the same source, above piston 6 causes a downward movement of the pistons and a corresponding opening movement from of the doors. The opening movement of the doors is cushioned by the air or other fluid under pressure which is-confined by means a of the check valve 33 between the large piston 6 and the small piston 7. Vfhile the pistons are moving downwardly the compressed fluid previously occupying the space in the upper chamber 8 of the diii'erential cylinder below the piston 6 is being compressed by reason of its diminishing volume incident to forcing the fluid confined between the pistons from the large chamber 8 of the difl'erential cylinder to the small chamber 9 thereof. The use of the check valve 33, while permittin entrance of pressure fluid to the space between the pistons, prevents egress of the fluid therefrom when its pressure is caused to exceed that of the service pressure under which fluid is supplied through the pipe 32. By means of this arrangement it is necessary only to maintain a constant supply of pressure fluid between the two pistons, the check valve permitting admission of additional fluid when necessitated by leakage, but the operation of the device requiring no supply of pressure fluid between the pistons other than that necessary to compensate for leakage. The air consumed in opthe piston heads being compensated for by the automatic entrance of air through the check valve 33.

7 While the gradual arrest of the downward movement of the pistons is in eflect acushioning action it is eflected by means quite different from the usual dash-pot arrangement in which the gradual retardation is efl'ected by the restricted outflow of the actuating fluid during the latter part of the piston stroke. During the operationof the device thefluid beneath the lower piston is in free communication with the atmosphere and plays no part in the retardation of the movement. At the beginning of the downward movement the fluid pressure per square inch upon the upper and lower faces of the large pistonand upon the upper face of the small piston is equal, this being the service pressure supplied through the check valve 33 to the space between the pistons and through the foot valve 37 and pipe 31 to the space above the-large piston. Under by reason of thedownward pressure upon the upper surface of the small piston, the upper surface of the large piston has an effective area equal to thatv of said smaller piston, to produce downward movement. The lessening of the effective under surface of the large piston by the cross-sectional area of the piston rod 11 may be neglected in this connection for the reason that the effective area of the upper face of the small piston is diminished by anr equal amount. The pressure downward on the uppersurface of the large piston is constant during the downward movementbeing the constantly supplied service pressure. The upward pressure on the lower face of the large piston, however, increasesduring the downward stroke proportionately to the increase of pressure due to the reduction of the volume of the fluid between the pistons and 1 the downward pressure upon the small iston increases in the same proportion. he downward movement continues until the u ward pressure on the. large piston equals t e sum of the downward pressures upon the large and small pistons. Such a condition of equilibrium is constantly approached and y brought about by the fact that the increasing pressure between the pistons acts upwardly on a larger area than downwardly. For this reason each increment of pressure per square inch between the pistons introduces a pre onderance of upward pressure to the difference in area of the large and small pistons. By this means the movement of the system is retarded on the downward stroke by the gradual approachof the oppositely acting fluid pressures to equilibrium and the movement terminates 40 when equilibrium is reached. The cushionmg of the downward movement is-eifected. without provision for the escape of .any of the fluid, thereby effecting substantial economy in the operation of the a paratus. Generally speaking, the compresse fluid between the pistons acts simply as a spring, be ing compressed beyond the service pressure during the downward stroke, and the extra tersthe s ace between the pressure so built up serves .both to cushion the opening movement and to efiect a quicker closing movement than would be caused by the service pressure'only. The only consumption of pressure fluid is that arising from the admission ,of fluid to the space above the large piston and its exhaust there from, vandsuch fluid'as automatically en-,

'istons when, owmg to lea age the pressure in that space falls be 0173215118 service pressure upplied through pie. Fig. 4 I have illustrated a. modified form of mechanism-fembodyin the-broad principle of my invention. he device shown in Fig. 4 is similar to that illustrated in Figs. '1, 2 and 3, but instead of confining "shown in v 32" which communicates the air between the large and small pistons I leave the space between the large and small pistons open to the atmosphere and confine the air within the-end of the small cylinder. 'Referring to Fi 4, the valve and port arrangement intl e'head of the large pylinder is the same as, that shown in 'Fig. 3, the means-for controlling the admission and exhaust of pressure fluid to the upper end of the large cylinder operating as above explained in connection with the form Figs. 1, 2 and 3. The lower end of the small cylinder in the modified structure isclosed by v confinin the fluid within the space between the smal piston 7 and the end of the small cylinder. Pressure fluid is supplied from a suitable source of pressure through a pipe with the small cyloint 102 adjacent the lower y means of an inwardly inder 101 at a end thereof.

opening check valve 103' pressure fluid 1s a permitted to flow from the pipe 32 into the small cylinder 101, but egress of pressure fluid therefrom is prevented. The pipes 32 and 31" are designed to be connected with a foot valve such as shown in Fig. 2, the connections of the pipes 32 and 31 with the foot valve being designed to be the same as the connections ofth'epipes 32 and 31 in Fig. 2. Aslot 104 in the side'ofthe cylin-. der structure between and small piston 7 admits atmospheric pressure to the space between the pistons and prevents compression of the am n said space. The slot 104 also-permits of an operative connection between the bar 105 con.- necting the large and small pistons with the door operating mechanism. The bar 105' upon the side thereof ad acent the slot 104 is provided with a series of teeth 106 forming'a rack. Door operating levers 107 and 109 are pivoted at 108 and 110to fixed parts of the mechanism. A segmental s 111 is formed upon the end of the ever 107 concentric with thepivot 108, a similar spur with the rack' teeth 106, but meshes with the large piston .62 I

ivot 110. The spur'gear the spur gear 111; .By this arrangement and an upward movement of the pistons causes a reverse movement of the levers.

a downward'movement of the pistons and their connecting rack bar causes the lovers. 107'and 109 to move away from each. other The levers 107 and 109 may be connected to the fire box doors by links113 and 114,. or by other suitable form of connection. In 0 ration admissionof pressure fluid eration of the foot valve as described in 'throug the pipe 31- is brought about by op- ,j y

1 to 3, and the pressure fluid entering the large cylinder through the duct 44' causes the pistons to move downwardly. The space 101 in the small cylinder is, as above stated, constantly supplied with fluid under pressure which enters through the check valve The downward movement of the pistons 103 but i prevented thereby from escaping.

' service pressure and thereby reaches a point where, though acting upon the smaller surface of the small piston, the upward force eventually counteracts the downward force, thus bringing the pistons to rest upon their downward stroke withoutshoclr. The

ing the closing movement of the doors. The,

broad principle of operation of the device shown in Fig. 4c is the same as that of the structure illustrated in Figs. 1 to 8.

What I claim is:

1. In a device of the class described cylinders of difierent diameters, operatively connected pistons in said cylinders, a source of fluid under pressure, means for moving said pistons in one direction by fluid supplied from said source, means for confining a body of said fluid under pressure between said pistons and for further raising the pressure thereof by said movement of said pistons, and means for exhausting the pressure fluid used to cause said movementof said pistons and eflecting reverse movement thereof by the expansion of said body of coinined fluid.

2. in a device of the classdescribed cylinders of diflerent diameters, operatively connected pistons in said cylinders, a source of fluid under pressure, means for moving said pistons in one direction by fluid supplied from said source, means for confining a,

body of fluid between said pistons and for causing said movement of the pistons to raise the pressure of said body of fluid be yond the pressure in said source, the expansive force of said confined fluid acting upon the larger pi ton in a direction opposite to said movement and upon the smaller piston in the direction of said movement, and means for exhausting said pressure fluid supplied from said source.

3. In a device of the class described, a

differential cylinde pe p 'ieg Chambers of diflerent diameters, connected pistons in said chambers and means for impelling said pistons in a direction towardthe chamber of lesser diameter, means for confining the fluid between said pistons when moving in said direction whereby saidmovement is gradually arrested by the compression of the fluid due to the lesser volume of the chamber of lesser diameter. 7

p 4:. In a device of the class described comprising a differential cylinder having chambers of diflerent diameters and connected pistons in said chambers, means for admitting fluid under pressure to the end of the chamber of large diameter remote from the chamber of small diameter and to the space between said pistons, thereby causing movement of said pistons in a direction toward the chamber of small diameter, means for preventing egress of fluid from the space between said pistons whereby said movement diminishes the volume and increases the pressure of the fluid between the pistons which increased pressure causes a gradually increasing resultant force acting to retard said movement of said pistons and to bring them to rest when equilibrium is established.

5. In a device of the class described comprising a differential cylinder having chambers of diflerent diameters and connected pistons in said chambers, means for admit: ting fluid under pressure to the end of the chamber of large diameter remote from the chamber of small diameter and to the space between said pistons, thereby causing movement of said pistons in a direction toward the chamber of small diameter, means for preventing egress of fluid from the space between said pistons whereby said movement diminishes the volume and increases the pressure of the fluid between the pistons which increased pressure causes a gradually increasing resultant force acting to retard said movement of said pistons and to bring fluid admitted to the end of the chamber of large diameter remote from the chamber of small diameter whereby the expansion of the fluid compressed between said pistons causes a reverse movement thereof;

6. In a device of the class described comprising a differential cylinder, having cham-. bers of different diameters and connected pistons in said chambers, means for admitting fluid under pressure to the space between said pistons and establishing low pressure in the space at the end of the larger chamber, thereby causing said plstons to move in a direction toward the larger chamber, means for admitting fluid under pressure to the space at the end of the larger chamber thereby causing reverse movement of said pistons, and means forccnfimng the fluid between said pistons during said reverse movement to thereby increase the pressure per square inch in the space between the pistons until it exceeds the service pres- 4 sure per squareinch, the total effective preswith the space in said cylinder between said pistons, a check-valve in said duct permittin flow of fluid only in a direction toward sai cylinder, and means for intermittently admitting fluid under pressure at the end of the larger chamber and hausting the Q.

8, In a device of the class described comprising to the space eaner? a difl'erential cylinder having chambersof difierent diameters and connected pistons in said chambers, means for impelling said pistons toward the smaller cylinder by fluid pressure in the end of the large cylinder remote from the small 0 linder, means for gradually arrestin sai movement b said plstons, means for causing reverse movement of said pistons by from the small-cylinder t ereby permitting expansion of the fluid between said pistons, and means for restricting said exhaust from said large cylinder before the completion of said reverse movement to gradua ly arrest said movement.-

the compression of uid between In testimony whereof I have subscribed my name.

JAY G. ROINSON.

exhausting the 1 fluid in the end of said large cylinder remote 

